Cali

The home screen shows your level and next day, a streak calendar in the style of Strava, stats for the last five workouts, your recent sessions and a weight curve with ranges from two weeks to a year. Everything is stored in the browser. With a Redis database and a shared code on Vercel, your phone and laptop keep the same history. It runs as a home-screen app on iOS, has a light and a dark theme, and comes in English and Danish: it follows the browser's language on first start, and you can switch in the settings.

The fiddly parts were the body figures (five SVG views with every path tagged by muscle group, and a rule for which view to show for each exercise), the sync (sessions are merged by id with tombstones for deleted ones, so a device can never bring back a workout you removed) and the screen transitions, which use the View Transitions API. Most of that work was removing flashes: flushing React inside the transition, only morphing the day title between screens that both have it, and leaving the browser's own back gesture alone. The screenshots and the video show eight made-up weeks of training.